In the past, various methods and apparatus were employed to effect indexing of work-pieces, such as a dynamoelectric machine for instance, between work positions at a work station for performing various manufacturing operations on the indexed work-pieces. Past mechanical indexing apparatus for effecting a "two stop" or 180.degree. index was usually accomplished by oscillation instead of indexing and consists of a simple rack and pinion mechanism driven by a servo motor, such as an air or hydraulic actuating cylinder or the like; however, one of the disadvantageous or undesirable features of this type of apparatus was that it produced an output movement having very poor acceleration and velocity characteristics. For instance, after the initial acceleration of the actuating cylinder during its stroke to its speed setting, the actuating cylinder thereafter operated at a constant velocity for most of the rest of its stroke, and at the end of its stroke, the actuating cylinder was stopped by an internal cushioning device and/or an external dash pot arrangement prior to the reversal of the stroke. Furthermore, it often happened that the driven load on the output shaft of the actuating cylinder was quite large in relation to the actuating cylinder size, and such out-sized load thereupon also became a driver, i.e., once it was in motion, requiring the internal cushioning device and/or external dash pot arrangement to stop not just the force of the actuating cylinder rod but the entire load being indexed which, of course, was also a disadvantageous or undesirable feature. In addition to the foregoing, another disadvantageous or undesirable feature of the past mechanical indexing apparatus was that minor variations in the driven load thereof, such as differing fixtures, part sizes, frictions, etc., resulted in irratic output motion of the actuating cylinder shaft which was especially noticeable or prevalent at the end of its stroke. Of course, efforts have been made in the past to overcome these deficiencies by increasing the size of the actuating cylinder and component parts associated therewith as well as increasing the stroke of the actuating cylinder; however, these part changes merely resulted in a rather bulky apparatus without appreciably correcting or affecting the aforementioned undesireable uniform velocity with high accelerations and decelerations of the output shaft. It may also be noted that geneva gear mechanisms are not capable of indexing an output shaft 180.degree..
U.S. Pat. Nos. 65,981, 595,732 and 3,459,056 each concern the conversion of non-harmonic acceleration of substantially linear reciprocal movement into generally harmonic acceleration; however, one of the disadvantageous or undesirable features thereof is that each requires dual inputs or drivers to effect the aforementioned conversion as well as a multiplicity linkages which are not only costly but also difficult to adjust and to maintain in the proper adjustment.